查看更多>>摘要：Electron beam selective melting (EBSM) is an additive manufacturing technique that directly fabricates three-dimensional parts in a layerwise fashion by using an electron beam to scan and melt metal powder.In recent years, EBSM has been successfully used in the additive manufacturing of a variety of materials.Previous research focused on the EBSM process of a single material.In this study, a novel EBSM process capable of building a gradient structure with dual metal materials was developed, and a powder-supplying method based on vibration was put forward.Two different powders can be supplied individually and then mixed.Two materials were used in this study: Ti6AI4V powder and Ti47Al2Cr2Nb powder.Ti6AI4V has excellent strength and plasticity at room temperature, while Ti47AI2Cr2Nb has excellent performance at high temperature, but is very brittle.A Ti6AI4V/Ti47AI2Cr2Nb gradient material was successfully fabricated by the developed system.The microstructures and chemical compositions were characterized by optical microscopy, scanning microscopy, and electron microprobe analysis.Results showed that the interface thickness was about 300 μm.The interface was free of cracks, and the chemical compositions exhibited a staimase-like change within the interface.
查看更多>>摘要：This paper emphasizes some of the challenges and trends associated with the future development of marine structures.Its main focus is on ways to improve the efficiency of energy-consuming ships, and on design challenges related to energy-producing offshore structures.This paper also discusses the analysis tools that are most needed to enable sustainable designs for future ships and offshore structures.The last section of the paper contains thoughts on the role of universities in education, research, and innovation regarding marine structures.It discusses curriculum requirements for maritime-technology education, basic research activities, and international cooperation.
查看更多>>摘要：Oxyfuel combustion with carbon capture and sequestration (CCS) is a carbon-reduction technology for use in large-scale coal-fired power plants.Significant progress has been achieved in the research and development of this technology during its scaling up from 0.4 MWth to 3 MWth and 35 MWth by the combined efforts of universities and industries in China.A prefeasibility study on a 200 MWe large-scale demonstration has progressed well, and is ready for implementation.The overall research development and demonstration (RD&D) roadmap for oxyfuel combustion in China has become a critical component of the global RD&D roadmap for oxyfuel combustion.An air combustion/oxyfuel combustion compatible design philosophy was developed during the RD&D process.In this paper, we briefly address fundamental research and technology innovation efforts regarding several technical challenges, including combustion stability, heat transfer, system operation, mineral impurities, and corrosion.To further reduce the cost of carbon capture, in addition to the large-scale deployment of oxyfuel technology, increasing interest is anticipated in the novel and nextgeneration oxyfuel combustion technologies that are briefly introduced here, including a new oxygen-production concept and flameless oxyfuel combustion.
查看更多>>摘要：The issues of reducing CO2 levels in the atmosphere, sustainably utilizing natural mineral resources, and dealing with industrial waste offer challenging opportunities for sustainable development in energy and the environment.The latest advances in CO2 mineralization technology involving natural minerals and industrial waste are summarized in this paper, with great emphasis on the advancement of fundamental science, economic evaluation, and engineering applications.We discuss several leading large-scale CO2 mineralization methodologies from a technical and engineering-science perspective.For each technology option, we give an overview of the technical parameters, reaction pathway, reactivity, procedural scheme, and laboratorial and pilot devices.Furthermore, we present a discussion of each technology based on experimental results and the literature.Finally, current gaps in knowledge are identified in the conclusion, and an overview of the challenges and opportunities for future research in this field is provided.
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